Abstract Exosomes are nanosized extracellular vesicles that contain biomolecules (DNA, mRNA, miRNA, and other functional proteins) from their cell of origin. Exosomes are secreted from nearly all cell types, and as a result, they are found in most biological fluids, including blood, saliva, urine, and cerebrospinal fluid. Over the past decade, the transfer of exosomal biomolecules to recipient cells has been implicated in a variety of biological processes. Consequently, exosomes have increasingly been the focus of many studies in biomedical research. Due to their distinct molecular signatures, exosomes have been identified as a potentially transformative circulating biomarker for the diagnosis and prognosis of multiple diseases, including cancer, neurodegenerative diseases (i.e., Parkinson?s and Alzheimer?s), as well as diseases of the kidney, liver, and placenta. In addition to diagnostic applications, exosomes are an ideal drug delivery system in many therapeutic applications. While the versatility of exosomes renders them an excellent candidate for a variety of biomedical applications, difficulties in the consistent, effective isolation of exosomes have greatly limited their utility. Current approaches for exosome isolation involve lengthy procedures, require highly trained personnel, suffer from low repeatability, low yield, low purity, and/or low post-sorting exosome integrity. As a result, there exists a critical need in the research communities for a simple, rapid, efficient, and biocompatible approach for isolating exosomes form biological fluids or in vitro cell culture. In this R01 project, we will address this unmet need by developing an acoustofluidic (i.e., the fusion of acoustics and microfluidics) platform for high-purity, high-yield, high-biocompatibility, automated exosome isolation. The proposed acoustofluidic technology will have the following features: 1) Automated exosome processing which reduces operator-to-operator variability and enables simple, consistent isolation results with improved biohazard containment; 2) Reduces the amount of time necessary to go from biofluid (e.g., 1 mL undiluted blood) to isolated exosomes (<5 min processing time vs ~8 hrs processing time with alternative technologies); 3) Higher exosome recovery rate (>90%) in comparison to benchmark technologies (5?25%); 4) Greater exosome purity (>80%) in comparison to benchmark technologies (~33%); 5) Less contamination from other circulating factors, including non-native serum proteins (e.g., albumin and immunoglobulin) and particles with similar sizes, including various types of lipoproteins; 6) Low-cost and point- of-care design; and 7) ability to handle both large and small sample volumes (maximum sample volume: ~30 mL; minimum sample volume: ~10 L), which is extremely challenging with existing approaches. With these unique features, the proposed acoustofluidic technology has the potential to greatly simplify and expedite workflows in exosome-related biomedical research and aid in the discovery of new exosomal biomarkers.